The Iowa State Fair is something of a right of passage for presidential candidates, featuring plenty of "down-home" photo-ops, a chance to share a pork chop on a stick with voters, and a bit of practice fielding the inevitable hecklers.
This year, more than a dozen candidates for president are scheduled take their turn on the soapbox, among them Republicans Jeb Bush, Scott Walker, and Marco Rubio. Democrats Bernie Sanders and Martin O'Malley will, too.
Hillary Clinton will attend the fair but has not yet said whether she will speak at the box.
The event can strip away formalities and reveal a more authentic and light-hearted side of the 2016 hopefuls. But it can also result in awkward moments and ill-timed soundbites.
"It's an important thing for candidates to do," Tom Henderson, chairman of the Democratic Party in Iowa's Polk County, told the Associated Press. "The pitfall is that in prior years, the real news story has been hecklers, which leads to quotes the candidates have to answer for."
In Mitt Romney’s 2012 campaign he said at The Des Moines Register's soapbox: "Corporations are people, my friend." The comment dogged Romney for the rest of his campaign.
O. Kay Henderson, an Iowa native who has covered candidates at the fair for Radio Iowa for more than 25 years, told NPR candidates must observe the three F’s.
"You have to pay attention to the food, you have to pay attention to the fashion ... and you have to avoid the faux pas,” she said.
Interactions between candidates and voters are often unusual.
At campaign stops in recent months, former Florida Governor Bush held hands and prayed with a flower-laden man in a top hat, Wisconsin Governor Walker embraced a sobbing homeless military veteran and former Secretary Clinton graciously accepted garlic pills from a supporter concerned for her health.
Presidential candidates will try to gauge where the state’s political affiliations currently lie.
Donald Trump holds the GOP lead with support from 22 percent of Iowans, according to a CNN/ORC poll released Wednesday.
"But over five months away from caucus night, top Iowa GOP strategists suggest it's still anyone's game. Hillary Clinton is holding a 50% to 31% lead over upstart Sanders, who is gaining ground in early-primary state New Hampshire,” CNN's Betsy Klein writes.
CNN notes the expected attendance of over one million means the event is essential for candidates in their attempt to court voters.
This report includes material from the Associated Press.